Such coupling elements and coupling assemblies as well as disc assemblies therefor are known from the state of the art. They are also known as disc couplings, because one or more disc elements are arranged between each of the connection elements for connecting rotatable machine parts, and in particular they serve for axial and angular compensation, they transfer torques, however, with low losses between the two connection elements and thus between the two machine parts to be connected. The couplings primarily serve to compensate angular and axial imprecision in the alignment of the two connection elements, or any connected machines relative to each other. The more rigid the disc assembly, the better is the torque transmission, but the lower is the tolerance when compensating the angular and axial misalignments.
Usually the connections to the surrounding connection elements are alternately arranged, which means, for example, that in a disc assembly having four attachment points, each even attachment point is fixed to the first connection element and each odd attachment point is fixed to the second connection element. This is continued with disc assemblies having more than four attachment points, wherein preferably each disc assembly has an even number of attachment points.
By coupling several coupling elements and preferably two coupling elements to form a coupling assembly in this way, various machine parts can be connected to each other in a torsionally rigid manner with high reliability and strict alignment tolerance.
As a general rule: the higher the power density, the speed or the number of load reversals, to which such a coupling element is exposed, the higher the requirements in terms of lack of play, tolerance and the precision of the fit of the parts connected with each other. The better the values that are achieved here, the higher the loads that can be applied to the coupling element and the more effective and loss-free is the transmission of torques.
To connect the disc assembly with each connection element, various embodiments and methods are known from the state of the art.
It is known, for example, to simply couple connecting elements with the disc assembly by means of frictional connections, such as by means of inserting compression bolts through complementary holes in the connection elements and the disc assembly and by clamping them by means of counter elements, such as nuts. A drawback in such embodiments is, however, the large play between the disc assembly and the connection element, so that torques are transmitted with greatly reduced efficiency.
To solve the problem, attempts have been made among others to use an interlocking connection instead of a frictional connection between the disc assembly and the connection elements, such as by pressing a compression bolt through complementary holes of the disc assembly and the connection elements. This guarantees improved power transmission. A drawback of such an embodiment, however, is that for insertion of the compression bolt a predefined relative positioning of the disc assembly and the connection elements with respect to each other has to be established. This is ensured among other things by fixing each element in an assembly apparatus, wherein the holes or recesses for inserting the compression bolts are provided after fixing. Since the dimensional accuracy of the holes in the disc assembly and the connection elements relative to each other is of critical importance, the disc assembly and the connection elements must not be released from the assembly apparatus prior to insertion of the compression bolt in the hole. This means that prefabrication and stockpiling of individual components is not possible. It is only possible to drill one fixed composition of a disc assembly and connection elements and subsequently immediately fix them with the compression bolt. This is costly and time consuming. Moreover, it has been found that, for interlocking pressing of the compression bolt, a cutting head is necessary on the free end of the compression bolt, which is also costly and time-consuming to manufacture. Moreover, should an error occur during pressing, the connection elements and/or the disc assemblies, or their individual discs, have to be disposed of as rejects, since renewed interlocking pressing of a compression bolt is no longer possible.
In order to prevent costly manufacture of cutting heads on compression bolts, it has also been known for compression bolts to be cooled down to such a degree that they can simply be fitted into holes in the disc assembly and the connection elements due to their reduced diameter. After reheating of the compression bolt, the result is an almost play-less interlocking connection between the disc assembly and the connection element. A drawback with this is, however, the time needed for cooling down and warming up the compression bolt and moreover the indispensable pre-positioning of connection element and disc assembly in an assembly apparatus to ensure play-less and precise arrangement of each of the components. A further drawback is that disassembly of the coupling elements or the coupling assemblies when using the above method is not possible or only very cumbersome and mostly involves the exchange of several components.
From U.S. Pat. No. 5,944,611, a coupling element of the initially mentioned type is known, in which a preassembled disc assembly is alternately connected to first and second connection elements via bolt connections. The disc assembly is fixed as a pre-assembled package via bolts to the connection elements.
DE 197 09 950 shows a similar arrangement. Again, for establishing a coupling element, a preassembled disc assembly is alternately connected to first and second connection elements as a package by means of bolt connections. The disc assembly has a plurality of discs fixedly connected to each other relative with respect to each other in the horizontal direction by means of a clamping sleeve flanged at the edge.
A similar coupling element is also disclosed in WO 2014/140128. Herein, fixing of a disc assembly preassembled as a package comprising a plurality of discs horizontally pre-aligned by means of a clamping sleeve, is established by means of bolts which are oversize to reduce assembly play between the disc assembly and the bolts, which is reduced as the disc assembly is fixed due to transverse contraction of the bolt.